1. Field of Invention
This invention concerns a product (a laminate) and manufacturing method for producing multishaped viaholes for making printed circuits that allow for conduction from conductor patterns that are applied to 1 or more layers of substrate. It also allows for producing solid post connections in certain design applications. The laminate can consist of metal clad reinforced meshes and such meshes are impregnated with a photoimageable dielectric insulating material.
2. Description of Related Art
This product and method can be used to produce single or doubled side circuits as well as multilayer circuit boards. Most manufacturers using widely applied common methods manufacture these circuit boards. These methods involve procuring a laminate such as 1 oz. copper clad epoxy reinforced laminate from a laminate producer. The laminate is mechanically drilled, vias are metal electrolessly plated or made conductive for example by graphite coating, photoimaged, electroplated, removal of the photo image and etched. More advanced product with tight tolerances e.g. 0.005" vias require variations on the above described process that are highly capital intensive and reduce the processing windows so that the capability of the vast majority of manufacturers cannot enter this market. An example of this limitation is the expense and limiting factor for drilling small holes. Mechanical drilling of holes less than 0.014" holes requires expensive drill bits and low levels of productivity. The alternative is laser drilling which is capital equipment intensive and beyond the means of a majority of manufacturers. In other cases expensive plasma equipment is needed to produce these tight tolerance designs.
An example of this is described in U.S. Pat. No. 5,022,956, Cziep et al. In this patent the process uses conventional laminate construction e.g. copper clad epoxy coated glass weave. It employs plasma to remove the dielectric. This following described embodiment does not require plasma and uses a photoimageable dielectric that does not require plasma or other expensive techniques to remove the dielectric. It further differs form Cziep et al in that the via can be positioned within the described etched metal opening to form any shape via desired. This allows for any size metal opening and subsequently a photoimaged via opening within the original metal opening. Cziep's vias are limited to size and shape of the metal opening. That is, Cziep's vias cannot be further defined and positioned as the current embodiment puts forth.